1. Field of the Invention
The present invention relates to a vehicular brake system comprising a braking force generating mechanism that generates a braking force when either a brake lever or a brake pedal is operated.
2. Description of the Related Art
Brake systems for motorcycles, scooters, ATVs, and the like often include a brake lever, a master cylinder, and one or more sets of brake calipers and brake discs associated with one or more wheels of the vehicle. For example, with a hydraulic brake system, such as the type disclosed in Japanese Patent Publication No. JP-A-2001-88766, when the front brake lever is operated (e.g., squeezed), a master cylinder assembly generates sufficient hydraulic pressure to cause a first set of brake calipers to close about a front brake disc and to cause a second set of brake calipers to close about a rear brake disc. Similarly, when the rear brake lever is operated, the master cylinder assembly generates sufficient hydraulic pressure to cause both sets of brake calipers to close about the front and rear brake discs. With such a brake system, both the front and rear brakes are operated regardless of when either of the brake levers is squeezed.
Some applications also include a brake pedal in addition to a brake lever to operate one or both set of the vehicle's brakes (i.e., the front and rear brakes). For example, an all-terrain vehicle (ATV) often includes a brake pedal in addition to a brake lever to provide the rider with more than one way to operate the brakes. In some uses, such as when traveling over a rough road, a rider may feel uneasy releasing his or her grip to operate the brake lever. In such cases, the rider can operate the brakes using the brake pedal. In other cases, such as when traversing a slope, a rider may want to use his or her leg and foot to help stabilize the vehicle on the slope. As such, the rider can operate the brakes using the brake lever while his or her leg and foot are used of other purposes during such maneuvers.
Japanese Patent Publication No. A-2000-313318 discloses a brake system in which the rear brakes are operated by either a hand-operated brake lever or a foot-operated brake pedal. The brake pedal includes an arm, which when moves, pushes a piston rod of an associated master cylinder. The master cylinder generates hydraulic pressure in the brake fluid which causes the rear brake calipers to close about the rear brake discs. The brake lever is connected to the arm by a wire cable. The wire transmits the force applied to squeeze the brake lever the arm, which in turn pushes the piston rod to apply a braking force on the rear wheels.
Rider acceptance of wire-operated brake system varies from individual to individual. Some riders dislike the feel of such systems when a hand lever is used to operate the brake. Over time, the wire lengthens and should be re-stretched to provide the original correlation between the braking force and the force applied to the brake lever. Additionally, it may become harder to squeeze the brake lever as the wire cable becomes dirty and warn. Accordingly, some riders prefer to use the brake pedal, rather than the brake lever, to operate the rear brakes.